It is well known that organosiloxanes which have long-chain alkyl groups linked to silicon atoms may be added to oils to depress their pour points. For example, DD Patent No. 115,916, teaches such additions to improve the cold behavior of liquid mineral oil products, especially of crude oil distillates such as diesel fuels, light heating oils and vacuum distillates, by adding thereto linear poly-n-alkyl-methyl-siloxanes of the formula (CH.sub.3).sub.3 Si--[OSi(CH.sub.3)R].sub.n --OSi(CH.sub.3).sub.3 with n.ltoreq.10 or cyclic poly-n-alkyl-methyl-siloxanes [OSi(CH.sub.3)R].sub.m with m=3 to 10 or mixtures of both classes of materials, in which R is a long-chain n-alkyl group with a chain length of C.sub.10 to C.sub.24 and preferably of C.sub.10 to C.sub.20. These additives are added to the mineral oil products in a concentration of 0.01 to 0.5 weight percent.
European OLS No. 0,113,579 describes an oil preparation, which comprises a greater amount of an oil having a viscosity of 5 to 30 cSt at 40.degree. C. and a lesser amount of an organopolysiloxane, the organopolysiloxane having the following formula: ##STR2## In this formula, R.sup.1 is methyl, ethyl or propyl, R.sup.2 is alkyl with 10 to 20 carbon atoms and n is a number from 12 to 28. The organopolysiloxanes depress the pour point of light mineral oil, their other important utilities especially their electrical properties, not being affected by the addition of the siloxanes. In particular, the dielectric losses, when the oils are used as insulating oils, are not increased by the addition of the siloxanes.
These organopolysiloxanes, known in the art, are however not or only insufficiently suitable for depressing the pour point of crude oil with a high paraffin content, especially a paraffin content of .gtoreq.10 weight percent. These paraffin-containing crude oils are extracted in very different oil fields, such as in India, in certain fields in the North Sea, in Egypt, the USA and Argentina and, because of their high pour point, cause considerable difficulties during transport and processing. These difficulties may be observed particularly in those crude oils, which contain n-paraffins with an average number of carbon atoms of .gtoreq.20. Admittedly, the pumpability of such crude oils may be improved by raising the temperature. This measure, however, frequently is frustrated by economic considerations or local factors. For example, it is hardly possible to heat pipelines which are laid under water.